Riser had the backing of the Republican establishment and Tea Party groups. McAllister was buoyed by endorsements from two local African-American leaders and the family featured in the popular reality television series Duck Dynasty.

One of the show's co-stars, Willie Robertson, appeared in one of his campaign advertisements just a few days before the election.

"I'm sure it certainly didn't hurt at all," McAllister said of the support he received from the Robertson family on Fox & Friends Monday. He went on to credit his win to the "100 percent positive" campaign he ran.

McAllister also may have benefited from the support of two black Democrats, Monroe Mayor Jamie Mayo and former Rep. Cleo Fields, who threw their support behind him. African-Americans make up as much as a third of the population in Louisiana's conservative 5th Congressional District.

The two candidates agreed -- as do most congressional Republicans -- that Obamacare should be repealed. But McAllister asserted that repeal isn't a realistic outcome as long as President Obama is in the White House and the Democrats control the Senate. So instead, he suggested, Republicans should focus on improving it.

That's a risky position for any Republican to stake out. But McAllister, a millionaire businessman, didn't stop there. He also came out in favor of expanding Medicaid -- a core tenet of the Affordable Care Act -- which put him at odds not only with Riser but with Louisiana Republican Gov. Bobby Jindal.

As the New Orleans Times Picayune reported, 21 percent of the district's residents did not have health insurance and 25 percent were living below the poverty line as of 2010.

Between his Obamacare stance and Riser's widespread political support -- the state senator had the backing of House Majority Leader Eric Cantor, three Louisiana House Republicans, the National Rifle Association and the Tea Party-aligned FreedomWorks -- McAllister was thought to be something of a long shot.

But he was running as a political outsider in a climate where public opinion of Congress is at an all-time low -- a Gallup poll released last week puts its approval rating at 9 percent.

He ended up winning easily, defeating Riser 60 percent to 40 percent to assume the seat left vacant by former GOP Rep. Rodney Alexander, who resigned in August to join Jindal's administration. Alexander had endorsed Riser in the election.

Despite his health care positioning during the runoff, McAllister is no moderate. During the campaign, he touted his support for gun rights, stated his opposition to abortion and same-sex marriage and pledged to investigate the Internal Revenue Service.